It is proposed to complete work on 1) the epidemiology of ectopic ventricular beats (VPB), and on 2) the influence of intervention upon habits thought related to their genesis. The background is based on the apparent triggering of sudden cardiac death by VPB. The frequency of VPB, their associations and prognostic importance in general populations outside hospital are explored here in detail. Because longterm safe anti-arrhythmic drugs are not available, a systematic trial is being completed to determine possible effects of avoiding stimulants, and improving autonomic nervous balance by sleep, avoiding alcohol and by conditioning exercise. This proposal is to complete collection and analysis of data in these descriptive and experimental studies now underway. BIBLIOGRAPHIC REFERENCES: Crow, R.S., Prinease, R.J., Dias, V., Taylor, H.L., Jacobs, D., Blackburn, H.: Ventricular Premature Beats in a Population Sample. Frequency and Associations with Coronary Risk Characteristics. Circulation, Suppl. III to 51 & 52, December, 1975, pp. 211-215. Blackburn, H., DeBacker, G., Crow, R., Prinease, R., Jacobs, D.: The Epidemiology and Prevention of Ventricular Ectopic Rhythms. Submitted to the Proceedings, Third Paavo Nurmi Symposium on Physical Activity and Coronary Disease, Helsinki, September, 1975.